Liquid projectile propellant for military ammunition



G.- D. CLIFT Nov. 15, 1960 LIQUID PROJECTILE PROPELLANT FOR MILITARY AMMUNITION Filed Sept. 12, 1952 Q mm INVENTOR. GILES D. CLIFT 75c. ATTORNEYS.

States LIQUID PROJECTILE PROPELLANT FOR MILITARY ANIMUNITION Giles D. Clift, 1012B E. San Antonio Drive, Long Beach, Calif.

This invention relates to improvement in military ammunition of the conventional fixed or semi-fixed types, its principal and underlying purpose being to provide either a hypergolic (ignitable on mutual contact) or nonhypergolic (requiring an igniter) bi-liquid propellant for the projectile.

Ammunition constructed on that order consists essentially of a cartridge case, a projectile secured in the otherwise open end of it and a compartmentation by which the components of the bi-liquid propellant are initially kept separated in the cartridge case. This general organization is suggested by the British patent to David Hodge and Alexis Ignatiefl, No. 405,645, but this patent lacks the detailed structure which is asserted herein as required for the effective carrying out of the principle of the invention.

Before going into those details it is thought desirable to briefly outline the background of modern use to which the invention can be adapted. In comparatively recent times, attempts have been made to reach and exceed the speed of sound with aircraft and missiles. As these efforts relate to military aircraft and with the probable successful development of the guided missile it is be coming evident that present anti-aircraft guns with relatively low muzzle velocity and rate of fire cannot be expected to successfully combat an air attack.

As an offset to that circumstance it becomes apparent that 'a most fertile field lies in increasing the muzzle velocity and rate of fire of defensive and ofifensive Weapons in this particular class. Experiments which have been conducted so far indicate that an inert projectile striking an aircraft structure with a velocity in the order of 7,000 is (foot-seconds) acts with a high explosive elfect on the structure, rather than clean penetration such as occurs at lower velocities.

However, solid propellants :have not as yet been developed which will yield this performance. Conventional single-base pyro powders with adiabatic flame temperatures in the order of 2,7 W. (Kelvin), if used at muzzle velocities in excess of 3,000 f.s. and rates of fire in excess of 40 to 50 rounds per minute in the case of a medium caliber anti-aircraft gun, result in adecrease in barrel life to approximately 100 rounds. Development of multi-base cool propellants have, so far, indicated that it is possible to obtain muzzle velocities in the order of 4,000 -f.s. and still retain satisfactory barrel life by using propellants having flame temperatures in the order of 1900 K.2,000 K. While it is feasible to manufacture multi-b-ase propellants with a flame temperature of 1,700 K., difiiculties of ignition and increased bulk have made their use undesirable. To obtain a muzzle velocity of 10,000 f.s., using presently known solid propellants, would require that the gun be built to withstand a breech pressure of 40 tons per square inch and would require a charge so large in physical size and weight as to make such a gun system impractical.

Liquid propellent systems seem to offer the only solution to the problem of developing an anti-aircraft gun atent having high muzzle velocity, high cyclic rate and satisfactory barrel life. For example, an experimental laboratory gun using a hydrazine-hydrogen peroxide propellent system has been developed and fired successfully numerous times in the order of 10,000 f.s. This gun, although requiring a revision of design in current types, has shown that it is possible to load liquid propellants into the breech at a predetermined rate so that the pressure is substantially constant within the gun during the travel of the projectile along the bore. Instead of the 40- ton p.s.i. breech pressure theoretically developed for a muzzle velocity of 10,000 is, the same velocity is derived from a liquid-propellent gun at a peak pressure of only half the foregoing amount. Moreover, after several hundred rounds of firing with the experimental gun no measurable bore enlargement has been found.

Thus, the advantages of the liquid-propellent projectile in respect to the gun that fires it are briefly summarized as follows: (a) increases the muzzle velocity over what can be expected from a conventional powder cartridge, (b) increases the barrel life over what is obtained with conventional powder cartridges, (0) eliminates smoke and flash, (d) offers the possibility of matching pressuretravel curve with the strength curve of the gun throughout its complete length, (e) enables continued use of present loading, handling and stowage facilities, (f) provides an alternate propellent source in the event of scarcity of materials during an emergency, and (g) insures a more uniform performance than before over a wide temperature range.

From the foregoing premises it can be understood that one of the objects of the invention is not only to provide a cartridge containing a liquid propellant for the projectile aflixed thereto, but also to disclose alternate ways by which the foregoing advantages can be fully realized.

Another object of the invention is to provide a cartridge of the character described, wherein a novel principle of extrusion is employed in the combining of the combustible components.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings herein:

Fig. l is a central, longitudinal section of a cartridge embodying the preferred form of the invention;

Fig. 2 is a fractional, sectional View of the same cartridge, illustrating the addition of a catalytic igniter;

Fig. 3 is a central, longitudinal section of a modified form of the cartridge; and Fig. 4 is a sectional. view of the cartridge in Fig. 3, illustrating a slight variation therefrom.

The invention is disclosed herein in two main forms; the form in Fig. 1 set up for a hypergolic propellant and the form in Fig. 2 set up for a non-hypergolic propellant. In other words, in Fig. 1 the components 10 and 11 of the propellant are such that when they are extruded from their isolated state and make mutual contact they automatically ignite and propel the projectile 12 from the cartridge case 13. On the other hand, in Fig. 2 the components, again designated 10 and 11, are such that ignition does not occur on mutual contact bu only on contact with a catalytic igniter 14. 7

Examples of the respective propellent components '10 and 11 in Fig. 1 are hydrazine, a colorless liquid hav-- ing a low freezing point, high specific impulse and other fuel properties, and hydrogen peroxide. 'When these liquids are mixed they immediately ignite and evolve a large volume of gas which propels the projectile 12 from its crimp 15 (or equivalent attachment) at the open end of the cartridge case.

Patented Nov. 15, 1960 The means by which this result is implemented consists of the following structure. A cast or molded solid propellent disk 16 is lodged at the base of the cartridge case on the inside. This disk may be a fuel-oxidizer or nitro-glycerine-nitrocellulose propellant. A primer 17 extends from the exterior of the base of the case 13 through the disk 16, and when the primer is detonated it ignites the inner surface of the disk.

As the solid propellant burns, gas is generated in the interior or internal space 18 of the cartridge, exerting pressure on each of two telescoped flexible bags 19 and 20 by which the fuel and oxidizer 11 are contained. One of the purposes of these bags is to keep the components 10, 11 separated until the cartridge is fired. Another purpose is to avoid a premature mixture which, obviously, cannot be allowed in the case of a hypergolic propellant. Still another purpose of the flexible bags is to provide an extruding means which will respond to the expanding gas in the space 18 and so drive the components out.

The bags 19, are desirably made of a suitable plastic fabric through which the liquid components will not migrate, for example, Pliofilm. As the expansion of gas in the space 18 continues the contents of the bags are forced through orifices 21 and 22 in the injector plate 23 that carries the bags. This plate is a partition that divides the space 18 from another space 24 in the cartridge that becomes the combustion chamber 24.

It is into this chamber that the contents of the bags are emptied, and the moment their contents come into mutual contact they ignite and set up a new and much higher pressure in the cartridge case to propel the projectile toward its target. Initially the orifices are plugged at 25 to seal the components 10, 11 in the bags, but when the extrusion commences these plugs are driven out. Eventually the two bags will be flattened against the back of the partition 23 and when that occurs one or both will be punctured to let the gas from the now consumed propellent disk 16 escape.

For the purpose of puncturing, at least one injector hole has a sharp projection 26 on the back face of plate 23 which produces a sharp, annular edge which will cut the bag or bags when collapsed to the limit. The puncturing means could also consist of a sharp, single point, and it would be located at a place beside one of the orifices. This arrangement is so easily visualized that specific illustration is thought unnecessary. The plugs 25 may comprise the stoppers shown, or they may be substituted by frangible disks which will rupture on a rise of internal pressure.

The bags 19, 20 extend away from the partition 23 about as shown. The inner bag 19 is secured at its mouth to the partition by such means as a clamp ring 19a. The partition occupies the mouth of the outer bag 20 which can be and desirably is headed at 20a. By pulling the partition with the bags assembled on it, toward the narrow end of the cartridge case there will be a clamping of the outer bag between the partition and the inside of the case.

Fig. 2 differs from Fig. 1 only in the addition of the catalyst 14. The reason for this employment, as brought out before. is that the bags 19, 20 contain a fuel and an oxidizer which compose a non-hypergolic propellant. The mode of extrusion of these components is identical with the showing in Fig. 1, but when they reach the chamber 24 combustion occurs only upon their contact with the catalyst 14.

Fig. 3 illustrates structure by which the effect in Figs. 1 and 2 is accomplished in a different way. Extrusion of the hypergolic components 10, 11 is now produced by two pistons, one a ring 27 the other a plug 28. The ring is best adaptable to the cylindrical form 29 of cartridge case shown in Fig. 3, all the others being tapered as can be seen. Since the ring is contrived to slide in a cylinder it may be made of somerigid material, for example,

iron or steel. The hole in the ring rides the outside of the concentric inner cylinder 30 aflixed to the partition plate 23, and the plug 28, also of rigid material, rides the inside of the same cylinder. The two cylinders contain the respective components of the propellant, and if this should be of the non-hypergolic type a catalyst would be supplied in the chamber 24 of Fig. 3 the same as in Fig. 2.

In Fig. 4 the variation from Fig. 3 is only to the extent of showing the adaptation of the ring 27a, which may be made of a compressible material, to a tapering cartridge case instead of to a cylindrical case since the ring 27a must travel the length of the oxidizer space to extrude its contents and since the annular diameter of the space diminishes because of the tapering case it follows that the ring must be deformable in character. It is made of a material such as a polyethylene plastic.

The plug 28 remains the same as in Fig. 3 since 39 is a cylinder in each of the piston types of extrusion means. From the foregoing description it is apparent that extrusion of the components of a liquid propellant by means of a gaseous plunger is a common principle throughout. This plunger is the product of the burning of the solid propellent disk 16 and it acts continuously on either the flexible bags 19, 20 or the ring and plug piston 27 (27a), 28. As these members crowd in upon the fuel 10 and oxidizer 11 the two components are driven through the orifices 21, 22 either by a squeeze or a push, and the seals 25 are broken to admit the components into the combustion chamber 24.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

The invention described herein may be manufactured and used by or for the Government of the United States for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. A cartridge consisting of a case closed at one end and having a projectile fixed in the other end, a partition fixed in the case and spaced from the projectile to provide a combustion chamber, a burnable substance lodged against the closed end and inside of the case, a bi-liquid propellant combustible in said chamber, separating means to keep the components of said propellant apart, being situated between the partition and the burnable substance, and a primer for igniting said substance to generate gas for the extrusion of the propellant through the partition into-the combustion chamber.

2. A cartiridge consisting of a case and a projectile, a partition fixed in the case and spaced from the projectile to provide a combustion chamber, said partition having sealed orifices, a burnable substance contained by the case, a bi-liquid propellant combustible in said chamber, means depending at least in part from the partition and separating the liquid components from each other, a portion of said separating means confronting the burnable substance to define a space, and a primer to ignite said substance to generate gas in said space, thereby to press on the confronting portion and extrude the propellant through the orifices after breaking the seals.

3. A cartridge consisting of a case having a projectile fixed in the otherwise open end thereof, a compartmented structure of flexible, collapsible material for separately containing the components of a bi-liquid propellant, a partition also fixed in the case and spaced from the projectile to provide a combustion chamber, the partition having said structure extending therefrom and having sealed orifices leading into the combustion chamber from 7 each of the compartments, a burnable substance in the fixed in the otherwise open end thereof, a compartmented structure of flexible, collapsible material for separately containing the components of a hypergolic bi-liquid propellant, a partition also fixed in the case and spaced from the projectile to provide a combustion chamber, the partition having said structure extending therefrom and having sealed orifices leading into the combustion chamber from each of the compartments, a substance burnable in the case behind said structure to collapse it and extrude its components into said chamber after breaking the seals, and a primer for igniting said substance.

5. A cartridge consisting of a case having a projectile fixed in the otherwise open end thereof, a compartmented structure of flexible, collapsible material for separately containing the components of a non-hypergolic bi-liquid propellant, a partition also fixed in the case and spaced from the projectile to provide a combustion chamber, the partition having said structure extending therefrom and having sealed orifices leading into the combustion chamber from each of the compartments, a substance burnable in the case behind said structure to collapse it and extrude its components into said chamber after breaking the seals, and a catalyst situated in the combustion chamber for igniting said components.

6. A cartridge comprising a case having a projectile fixed in the otherwise open end thereof, a pair of flexible, collapsible bags for separately containing the components of a bi-liquid propellant, a partition also fixed in the case and spaced from the projectile to provide a combustion chamber for said components, the partition having said bags extending therefrom and having sealed orifices leading into the combustion chamber from each of the bags, a substance burnable in the case behind said bags to provide gas pressure to collapse the bags and extrude their components into said chamber after breaking the seals, and means erected from the partition on the side next to said bags to puncture at least one of them at the limit of collapse for the release of said gas pressure.

7. A cartridge comprising a case having a projectile fixed in the otherwise open end thereof, a telescoped pair of flexible, collapsible bags for separately containing the components of a bi-liquid propellant, means for generating gas behind the bags to collapse them and extrude their contents for combustion, and a partition fixed in the case and spaced from the projectile to define a combustion chamber to receive said components, the mouth of the inner bag being secured to the partition, said partition occupying the mouth of the outer bag and clamping it against the inside of the case so that both bags extend from the partition, the partition having sealed orifices leading into the combustion chamber from each of the bags.

8. A cartridge having a projectile, a compartmentation to contain the components of a bi-liquid propellant, said compartmentation comprising a cylindrical case in the otherwise open end of which the projectile is fixed, a concentric cylinder annularly spaced in from the case, a ring and plug piston heading one end of the annular space and the concentric cylinder, a partition fixed in the case and spaced from the projectile to provide a combustion chamber for said components, said partition having the concentric cylinder afiixed to it and having 6 sealed orifices leading into the combustion chamber from the annular space and from the concentric cylinder, and means for generating gas behind the ring and plug piston to extrude said components into the combustion chamber after breaking the seals.

9. A cartridge having a projectile, a compartmentation to contain the components of a bi-liquid propellant, said compartmentation comprising a tapering case in the otherwise open and narrow end of which the projectile is fixed, a cylinder annularly spaced in from the case, a ring and plug piston heading one end of the annular space and the cylinder, a partition fixed in the case and spaced from the projectile to provide a combustion chamber for said components, said partition having the cylinder aflixed to it and having sealed orifices leading into the combustion chamber from the annular space and from the cylinder, and means for generating gas behind the ring and plug piston to extrude said components into the combustion chamber after breaking the seals, said ring being composed of deformable material which will yield compressively to the taper of the case.

10. In a gun cartridge having a tubular case closed at its rear end by a base and at its front end by a projectile, the improvements in combination comprising; wall means within the case forming a plurality of separated chambers, a pair of said chambers being propellant chambers, one containing a component of a liquid bi-propellant and the other containing another component of the liquid bi-propellant, said propellant chambers being reducible in volume, and another of said chambers being a void space adjacent the projectile forming a combustion chamber, a burnable substance within the case adapted to produce gas under pressure for reducing the volumes of the propellant chambers, and means communicating the propellant chambers with the combustion chamber when the former are reducing in volume, whereby the components of the liquid bipropellant are delivered to the combustion chamber for reaction therein to thereby produce gas under pressure for propelling the projectile from the case.

11. A cartridge in accordance with claim 10 wherein said propellent chambers are disposed adjacent and rearwardly of the combustion chamber, and said burnable substance is in a chamber disposed between the cartridge base and the rearward portions of the propellent chambers.

12. A cartridge in accordance with claim 10 wherein the liquid bi-propellant is hypergolic.

13. A cartridge in accordance with claim 10 wherein the liquid bi-propellant is non-hypergolic, and means within the combustion chamber for initiating reaction of the bi-propellant.

References Cited in the file of this patent UNITED STATES PATENTS 2,433,932 Stosick Jan. 6, 1948 2,505,798 Skinner May 2, 1950 FOREIGN PATENTS 197,518 Great Britain May 17, 1923 721,289 Germany June 1, 1942 272,168 Switzerland Feb. 16, 1951 

